Various control arrangements are known from the state of the art with which the forward propulsion speed or the intake velocity of an intake arrangement of a harvesting machine can be controlled.
EP-377163 A reveals a control arrangement of a harvesting machine in which the intake arrangement is driven at a speed that is proportional to the forward propulsion speed, where the proportionality factor is a function of the type of the particular intake arrangement. DE-19509496 A proposes that the rotational speed of the reel of a combine be controlled as a function of the forward propulsion speed according to a non-proportional characteristic, that is stored in a memory, which produces a higher speed advance for the reel at lower forward propulsion speed and a lower or smaller speed advance for the reel at higher forward propulsion speed. According to EP-812530 A, the rotational speed of the reel can also be a function of the height of the cut.
DE-2915531-A describes a harvesting machine in which the forward propulsion speed is controlled in such a way that a constant density of the grain loss material delivered by the harvesting machine results. Similarly, DE-2753813 A proposes the measurement of load changes in cutter, conveyor, threshing or separating arrangements of the combine and to use these for the control of the forward propulsion speed; the aforementioned load should remain constant. DE-2436072-A discloses a harvesting machine in which the forward part of the cutter head is provided with one or more touch sensor arrangements, which detect the amount of the crop to be processed and control the forward propulsion speed of the harvesting machine. According to DE-4320977-A, the measured grain separation at the thresher stator and the measured grain separation at a sieve of the separating arrangement are used to control the forward propulsion speed of a combine, which are used as a function of time.
DE-1582177-A reveals a combine in which the conveying speed of the intake arrangement is controlled as a function of the forward propulsion speed in such a way that a constant throughput of the crop is attained. IN GB-2155666-A, the forward propulsion speed is varied so that the rotational speed or the torque of a chopper drum remains constant.
U.S. Pat. No. 4,487,002 describes a combine that is provided with a sensor for the throughput of harvested crop, which measures the power applied to the slope conveyor. In addition, the rotational speed of the engine and the forward propulsion speed is measured. These measured values are transmitted to a control circuit that controls the forward propulsion speed and attempts to hold the engine at a constant controllable speed. If the load on the conveyor increases due to harvested crop beyond a threshold value, the actual forward propulsion speed is controlled primarily as a function of the rotational speed of the engine, so as to maintain the desired rotational speed. In case that the load does not increase above this threshold value, that is, no harvesting is performed, but operation on a road is performed, the actual forward propulsion speed is primarily a function of the selected vehicle speed. The combine is braked rapidly when a second threshold value of the throughput is exceeded, that is when a blockage is threatened.
Therefore, it is desirable that the forward propulsion speed of the harvesting machine is controlled in such a way that the power output of the engine or the rate at which the crop is processed remains approximately constant. Such a method of operation is particularly economical.
However the density or the height of the crop varies on occasion so sharply that the known control arrangements result in sudden jumps or frequent corrections to the speed. Upon sudden increases in the torque due to local increases in the density of the crop, the rotational speed of the engine drops and is followed by a correction in the forward propulsion speed. The result is that less crop is conveyed into the machine for a brief period and thereby the torque of the crop processing arrangement can again return to normal. From its torque reserve, the engine can again return to its original operating rotational speed by briefly increased fuel consumption. Her the increased fuel consumption as well as the mechanical loads on the driveline and torque transmitting components due to load fluctuations can be seen as detrimental. In addition, the continuing acceleration and retarding processes are uncomfortable for an operator sitting on the machine.